Oscillating apparatus



April 24, 1951 D. F. MANERS OSCILLATING APPARATUS Filed Sept. 3, 194'.

Patented Apr. 24, 1951 OSCILLATING APPARATUS David F. Maners, San Francisco, Calif., assignor,

by direct and mesne assignments, to Beautymaster, Inc., a corporation of California Application September 3, 1947, Serial No. 771,948

7 Claims.

My invention relates to oscillators, and particularly to oscillators adapted to supply small currents at relatively low frequency to produce muscular contractions and thus give passive exercise where this is therapeutically desirable.

Among the objects of my invention are to provide equipment which is safe for home use by the patient, and because of its inexpensive construction can easily be afforded by the average family for such home use; to provide an oscillator which, because of the unusual wave forms generated thereby, produces a high degree of stimulation with relatively small voltages and currents, which are well within the limits which unskilled personnel can safely handle; to provide an oscillator the output of which is limited to such small currents and voltages, and is so isolated from the supply circuits that there is no possibility of shock from the supply circuit; and to provide a device wherein the oscillations supplied can be automatically and rhythmically interrupted at a controllable rate so that the muscular contractions produced can be timed to meet the particular requirements of the muscles to be exercised.

Considered broadly, the oscillator of my invention comprises a vacuum tube, preferably a triode, the grid and anode of which are connected respectively to the primary and secondary windings of a transformer. The other end of the primary winding is connected to a fairly high positive potential with respect to the cathode; e. g., to the opposite side of the usual 110120 volt domestic supply. Such supply can be either D. C. or A. 0., for if it be the latter the device operates on alternate half cycles, which appears to make no differencein the muscular effects produced.

The distinguishing characteristic of the circuit is that the secondary connects to the cathode without the interposition of any external supply of plate current and voltage. A resistive circuit to control the intensity of oscillation may be included in this circuit, and means may be provided for rhythmically interrupting the oscillations to give continuous exercise. The oscillating currents are applied where desired from an insulated tertiary winding on the transformer which couples the anode and grid circuits.

The invention and its mode of operation can be more clearly understood from the detailed description of a preferred embodiment which follows, together with the accompanying drawings, wherein:

Fig. 1 is a circuit diagram of the device as constructed for alternating current operation, and

Fig. 2 is a reproduction of the potential wave produced, as displayed on the screen of a cathode ray oscilloscope with its sweep circuit synchronized with the 60-cycle supply current.

Considering first the oscillator proper, it comprises a triode I having an anode 3, grid 5, cathode l and heater 9. The heater is connected across the A. C. supply lines iI-IZ through a resistor i3 (for reducing the heater current to its proper value), and a filament switch l 5 may conveniently be included in this circuit. The supply lead i i will, on occasion, hereinafter be referred to as the positive side of the line and the lead l2 as the negative side, since this relationship holds during the half cycle of the suppl voltage when the oscillation occurs. The device is dead during the other half cycle.

Grid 5 connects to the positive lead ll through the primary coil ll of a transformer iii. A small condenser 25 (about .01 mmf.) is preferably bridged across the coil i'i, since this suppresses radio interference which the oscillator otherwise may cause. The cathode I connects through a lead 23 to one arm 25 of a S-pole, 3-position switch. In the position shown, where only the basic circuit of the oscillator is employed, the arm 25 contacts the switch point 2'! which connects directly with the negative lead 62. The grid circuit then can be traced from the positive side of the line through the coil l! to the grid 5, thence through the space path of the tube to the cathode, and so through lead 23, switch arm 25 and point 2'! back to negative line I 2.

To trace the plate circuit we may start with the negative lead 8 through the second switch arm 29 and point 3! to the lower end of the secondary winding 33 of transformer H, the upper end or" which connects to the anode 3. The anode bias potential is therefore the potential of the cathode; there is no potential in the anode circuit except what is induced from the primary of the transformer I 9. The ratio of primary to secondary of the transformer is about 3:5 in the specific apparatus described, but is not critical.

The mechanism of oscillation in the active half of the cycle appears to be as follows:

The grid 5, connected to the positive side of the line, starts to draw current, thus imposing a positive potential on the end of the transformer primary i! to which it is connected and inducing a higher positive voltage in the secondary 33 which appears on the anode. The discharge promptly transfers to the latter, and because of the amplifying characteristic of the tube and the relatively low resistance of the plate circuit as compared to the grid circuit induces a voltage which swings the grid toward the negative and cuts off the flow, whereupon the cycle repeats. The potential developed in the plate circuit is shown in Fig. 2. Oscillation starts when the grid reaches a critical positive potential, which occurs at about 45 electrical degrees. The build-up of potential is very rapid; after reaching a sharp peak the potential falls off with increasing rapidity to a negative peak, following which it swings again toward the positive along an approximately exponential curve until the critical initial volt-. age is again attained, when the action repeats. With the circuit constants as here described four complete oscillations occur in each active half cycle of the supply current, the rate of the oscillation therefore being nearly 1000 cycles per second.

The currents thus generated are appliedto the patient through a tertiary coil 35 on the transformer iii. The turn ratio of this coil with re spect to the primary is about 1:2 in the device described, being about '100 turns of wire on a one-half inch square core. In this embodiment the tertiary is closed through a 400 ohm potentiometer, and moist pad electrodes 35 connect to I the movable contact and one end of the potentiometer respectively.

It is evident from this arrangement that the actual power that can be'delivered to a patients body is very small. The currents will not registeron the thermocouple or hot wire instruments such as are available in most radio laboratories, and'special sensitive instruments are necessary if they-are to be measured. The voltages indicated'by ordinary instruments are also small, but a peak voltmeter shows that instantaneously the voltage rises enough to explain the physiological effects. The point is that the currents which flow are aiways too small to cause any danger to the patient. 7

As thus far described the instrument produces a continuouscontraction of the muscles. While thisis-desirable for some forms of treatment the efiect of regular exercise is better produced by applying the oscillations in pulses, and the device as shown has means for producing such pulses of varying length, over two ranges, electronic means for pulsing, at rates of from about per second to about 1 /2 seconds, and electromagnetic means for producing pulses of longer du-ration,say up to 5 seconds or more.

For the rapid pulses the three-pole switch is turned to connect the'arm '25 with contact 4!, which, being in parallel with contact 21, does not alter the grid-cathode circuit. This same position of the switch brings arm 29 into connection with contact 43, which cuts a timing circuit into series with the anode, cathode and transformer coil 33.

The timing circuit comprises a condenser 45, of the order of 50 mi. capacity, shunted by a resistor 51 of about 100,000 ohms, both in series with an adjustable resistance 49 whose maximum value may be about 250,000 ohms. The current pulses in the coil 3-3 are, of course, rectified. These pulses charge the condenser to a point where the oscillations are blocked, and remain so until the charge has leaked oiT. The rate of both charge and discharge is controlled by the rheostat 49, through the more rapidrange above specified.

For longer timing the switch blades and 29 are'turned to contacts 51 and 53 respectively, which brings switch arm 55 in contact with a switch point 57, this latter arm having been on unconnected points in the switch positions previously described. In this last switch position the timing circuit is shorted out by the switch arm 29, leaving the anode circuit as first described, and pulsing is accomplished by periodically opening and closing the grid-cathode circuit.

The latter circuit can ,now be traced from line II to the grid 5 and the space path to cathode l, thence through arm 25 and contact 5| to a lead 59 which connects to lower contact SI of a relay 63, and so back through lead and switch arm 25 to the negative line 52.

The relay is actuated by a side circuit which. starting from lead II and switch arm 55, continues through a lead 61 to the anode 69 of a diode rectifier I i, through the space path to the cathode l3, and then through the center tap of filament transformer 15 through the relay coil and back to line 55. The primary of the filament transformer is excited through a branch circuit from line 5-7 to relay contact 1'! and the relay armature to line 65. The contacts may be bridged by a condenser 19 and resistor 8| to suppress radio interference.

The timing of the relay operation is controlled by a condenser83 in series with a high resistance rheostat'85, shunted across the winding of relay 53. When the diode is first excited the rectified current it passes first goes tooharge condenser rather than passing through the relay coil. As the condenser becomes charged, however, an increasing amount of current passes through the coil until finally the relay operates, closing contact 5! and exciting the oscillator circuit, and at the same time openingthe filament transformer circuit of diode II. The latter then ceases to rectify as the cathode cools, condenser '83 loses its charge and the relay releases, starting the cycle over again. The length of the relay cycle is controlled by the 'rheostat 85.

It will be clear that pulses of as long duration as those obtained by the relay circuit just described could be obtained by increasing the timeconstant of circuit 4541-4 9 and also that other methods of pulsing can be used with the oscillator of my invention. For certain purposes therapeutists appear to prefer the sudden stopping and starting of the oscillations obtained by the relay pulsing'rather than the more gradual waxing and waning provided by the time constant circuit. I do not wish to be limited to any specific method of pulsing the oscillator here disclosed, nor are the circuit constants mentioned in the description to be considered as more than merely illustrative, since they can be varied over a wide range. I desire tobe limited in my protection on this invention only as limitations are expressed in the following claims.

I claim: 7

'1. An oscillator comprising a vacuum tube having an anode, a cathode and a grid, a circuit connected to apply a positive potential to said grid with respect to said cathode, a transformer having a primary winding connected from said grid to said cathode through said circuit, and a step up secondary winding connected from said anode .to said cathode to maintain said anode and cathode at the same mean potential and to induce on said anode a positive potential upon increase of current in said primary winding, and means for applying oscillating potentials developed by said transformer windings to a load circuit.

2. An oscillator in accordance with claim 1 including a resistive timing circuit in series with said secondary winding.

3. An oscillator in accordance with claim 1 including a resistor-capacitor circuit of variable time constant in series with said secondary winding.

4. An oscillator in accordance with claim 1 wherein the final means mentioned therein comprises a tertiary winding isolated from the primary and secondary windings thereof.

5. A device for passively exercising muscles by electrically stimulated contractions comprising an oscillator in accordance with claim 1 and means for regularly and periodically interrupting the oscillations thereof at a controllable rate.

6. A device for passively exercising muscles by electrically stimulated contractions comprising an oscillator in accordance with claim 1 and means for periodically opening the circuit connecting the cathode and the grid at a controllable rate.

'7. A device for passively exercising muscles by electrically stimulated contractions comprising an oscillator in accordance with claim 1, a relay connected to interrupt the operation of said oscillator, and an actuating circuit for said relay comprising circuit connections for supplying alternating current thereto, a rectifier in series with said relay connected in said supply circuit, and a resistor-capacitor circuit of variable time constant connected across the winding of said relay.

DAVID F. MANERS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,044,003 I-Iollmann June 16, 1936 2,048,752 Osnos July 28, 1936 2,181,568 Kotowski Nov. 2-8, 1939 2,193,850 Andrieu Mar. 19, 1940 2,210,669 Johnson Aug. 6 1940 2,411,573 Holst Nov. 26, 1946 2,464,259 Proskauer Mar. 15, 1949 

